GB2132353A

GB2132353A - Ultrasonic inspection equipment

Info

Publication number: GB2132353A
Application number: GB08236093A
Authority: GB
Inventors: William Raymond Clipson; David Justin Corcoran
Original assignee: MATEVAL Ltd
Current assignee: MATEVAL Ltd
Priority date: 1982-12-18
Filing date: 1982-12-18
Publication date: 1984-07-04

Abstract

Ultrasonic inspection equipment has a plurality of probes (54) of the same basic form at different angles in a common block (50). The probes are cylindrical and are removably fitted in accurately machined stepped bores (51). In assembly the probes are fitted with their shoes (30) projecting from the under surface (57) of the block and this surface is then skimmed so that the transmitting surfaces (31a) lie in the under surface (57). For repair, a faulty probe is removed from the block, a new probe is inserted, and the under surface (57) re-skimmed to remove the projecting shoe. <IMAGE>

Description

SPECIFICATION Ultrasonic inspection equipment This invention relates to ultrasonic inspection equipment and it is concerned with such equipment having multiple or grouped ultrasonic transducers or probes.

It is already appreciated that ultrasonic inspection equipment having multiple (typically up to 240) transducers or probes can be made and used in manipulators for the high speed inspection of large areas. The ultrasonic signals can be multiplexed and each channel gated and digitised for real time signal analysis or storage on tape or disc. Such equipment used individual probes, each probe comprising a crystal on an appropriately machined face of a transmitting component (usually called a "wedge"). The individual probes are held together in one or more support structures (usually called a "pan"). A typical pan may contain any number of individual or multielement probes. The actual number of probes required is determined by the particular application. ideally there would be sufficient probes to effect the inspection in a single pass of the manipulator.

A pan usually contains at least one compression wave probe (00) which is used for coupling monitoring, and several shear wave probes which search for defects. These search probes may have any angle as determined by the application, but are generally in the range 450 to 900.

Such a pan operates satisfactorily. The quality of performance can be enhanced if greater cost can be accepted in order to select probes meeting closer tolerances. Should one probe in a pan become faulty it can be replaced but this does require a holding of at least one spare probe of each variety used in the pan. This can be costly and troublesome especially where the equipment is being used in a remote and possibly hostile site as frequently occurs for example with pipe line testing.

The present invention is directed to the matter of reducing costs whilst satisfying a need for closer tolerances; reducing the holding of spares; and simplifying replacement of probes in a group.

According to the present invention, ultrasonic inspection equipment having multiple or grouped probes is characterised in that probes performing different functions have a common basic form and are removably fitted in accurately machined bores in a common block with their transmitting faces on a common surface.

The invention will now be described further with reference to the accompanying drawing in which: Fig. 1 shows, in sectional eievation, one known form of probe which can be assembled with other forms in a pan; Fig. 2 shows a basic form of probe which can be used in common with others in equipment according to the present invention in a common block: Fig. 3 is a cross-section of common block equipment according to the invention; and Figs. 4A and 48 taken together show a plan view of the common block of Fig. 3.

In Fig. 1 a wedge 20 of "PERSPEX" (Registered Trade Mark) (methyl methacrylate) has an inclined face 21. The face 21 carries a crystal 22 and damping material 23. A protective case 24 encloses the wedge, crystal and damping material.

A coaxial terminal 25 is provided for the probe.

The probe is shown supported above a weld 26 in a component 27 to be inspected. The refracted beam 28 of ultrasonic energy is also shown. The probe is caused to move along the weld together with other probes having other face 21 inclinations to give other angles of refracted beam.

In Fig. 2 the probe has a methyl methacrylate cylinder or shoe 30 with an end transmitting face 31 which is normal to the axis of the cylinder. A crystal 32, damping material 33, and insulator 34 are carried on the other end face of the cylinder.

An upper case 35 and cap 36 enclose the crystal and damper. A terminal 37 is provided for powering the probe. A cable 38 is shown connected to the probe and wires 39, 40 run from the terminal to the crystal. A resistor 41 and inductor 42 are in series between wires 39, 40.

In Fig. 3 (which is of reduced scale relative to Fig. 2), the section of a common block 50 is shown together with one accurately machined bore 51 with a step 52. A probe 54 (as shown in Fig. 2) is removably and accurately fitted in the bore so that the end of the lower end of the case 35 of the probe abuts the step 52. The probe is securely retained in the bore 51 by a locking screw (not shown) fitted in a threaded bore 55.

The block also has a bore 56 by which it can be mounted for movement in use.

The bore 51 has a very precise inclination, close diametral tolerance, and accurate location of the step 52. These can be achieved as straight forward machining operations using a jig borer.

The probe is a close push-fit in the bore 51.

As Figs. 4A and 48 show the block 50 has multiple bores 51 and when all the probes 54 have been fitted in the bores the shoes of the probes project from the under-surface 57 of the block as indicated by the dash line 30 in Fig. 3.

This procedure leaves a number of projections of shoes 30 from the under surface 57 of the block 50. When all the probes are in place this under surface is skimmed so that the transmitting surfaces 31 a of the shoes 30 are on a common surface.

Returning to Figs. 4A and 4B, the common block 50 is shown having ten bores numbered 1 to 10. Bore No. 1 provides a compression probe location and the remainder show shear probe locations.

Should a probe become faulty then the screw in the appropriate bore 55 can be released and the faulty probe removed from its bore and simply replaced with a new probe as shown in Fig. 2 and the under surface 57 is reskimmed. As the probes are common, the stocks held for repair may be quite small. Assembly of the probes has become simplified and more routine and hence a higher standard can be achieved without comparable cost increase. The angles of the probes in the common block are very close defined in relation to each other and to the block 50.

The material of the block 50 can be chosen depending on the duty to be performed. For example, when inspecting aluminium, a "PERSPEX" block can be chosen as it is soft and will not damage the aluminium. For inspecting steel an aluminium block can be used.

Claims

1. Ultrasonic inspection equipment have grouped probes performing differing functions, characterised in that the probes (54) are removably fitted in accurately machined bores (51) in a common block (50) with their transmitting faces (31 a) on a common surface (57).

2. Equipment as claimed in claim 1 in which the probes are of cylindrical form and each includes a step where a shoe (30) of the probe projects from a case (35) of the probe, said steps abutting corresponding steps (52) in the bores of the block.

3. Equipment as claimed in claim 1 or 2 having a bore (56) in the block whereby the equipment can be mounted for movement in use.

4. Ultrasonic inspection equipment substantially as hereinbefore described with reference to Figs. 2, 3 and 4 of the drawings.

5. A method of making ultrasonic inspection equipment as claimed in claim 1 in which probes are fitted and held in the machined bores with shoes (30) projecting from the common surface (57) and said surface is skimmed to remove the projections and leave the transmitting faces (31 a) on said common surface (57).